What is an Operating System?

Administrator

Description

• mémoire - matière potentielle : pkmemorypkmemory pjmemorypjmemory
• mémoire - matière potentielle : management
• mémoire
• mémoire - matière potentielle : protection
• mémoire - matière potentielle : space
• mémoire - matière potentielle : resource
• mémoire - matière potentielle : address
• mémoire - matière potentielle : access
• mémoire - matière potentielle : space with a new program
• expression écrite
• mémoire - matière potentielle : location
• mémoire - matière potentielle : leak

Operating Systems 9/3/2009 CSC 256/456 - Spring 2007 1 9/3/2009 CSC 2/456 1 Computer System Organization CS 256/456 Dept. of Computer Science University of Rochester 9/3/2009 CSC 2/456 2 What is an Operating System? • Software that abstracts the computer hardware – Hides the messy details of the underlying hardware – Presents users with a resource abstraction that is easy to use – Extends or virtualizes the underlying machine • Manages the resources – Processors, memory, timers, disks, mice, network interfaces, printers, displays, … – Allows multiple users and programs to

• vm native vm
• vm monitor
• exclusive address space
• user programs
• device
• memory
• management
• hardware
• system
• program

Sujets

• Management
• Mémoire
• Protection
• Resource
• Address
• Access
• Location

Informations

• Publié par: orzi
• Nombre de lectures: 14
• Langue: English

Extrait

THE SNOWBALL




by
EREMEI PARNOV, MIKHAIL EMTSEV






Translated from the Russian by Gladys Evans

From the compilation “JOURNEY ACROSS THREE WORLDS”

Mir Publishers
Moscow
1973


___________________________________________________
OCR: http://home.freeuk.com/russica2




The wallet in my pocket holds my passport, work-pass, and a few society
membership cards showing paid-up dues—yet I, myself, am only a phantom,
a transitory corporeal image. I really shouldn't be walking along this snow-
covered pavement, or breathing this pungent, crystalline air. Even the most
deprived of the deprived, devoid of all life's blessings, locked forever in
prison, has more rights than I. Immeasurably more.
So I keep thinking ... though I'm not always quite sure of it. I'm too well
acquainted with the world around me, too used to it, to be really sure. The
tree branches are puffed with hoarfrost and look like horns of young deer.
The electric and telephone wires are almost invisible against a pallid sky,
though they are as thick and white as manilla rope. The TV antennas on the
roof of the physics faculty building look frozen in the wan light of oncoming
evening. Resembling the masts of a ghostly frigate. The chemistry faculty
advertises its presence with the queer smell of elemento-organic ether—I
never can decide whether it is pleasant or odious. An ordinary everyday
world! And only my memory, twisted into a knot of nervous alarm, squeezes
my heart and whispers:
All are dreams, all chimeras that pass,
As if reflected in a looking-glass—
Days forever spent and gone.

Yesterday it was still summer, but today it is winter. How many
deceptions there are in that word 'yesterday'. No, it wasn't yesterday....
I have no overcoat. To be more exact, it is hanging somewhere in the
cloakroom, but the number tag is in a stranger's pocket. Again a deception:
'in a stranger's'. Not a 'stranger's' .... The simple truth is that we haven't
devised the right word for it, not yet. I walk fast so as not to freeze. I'll
manage without a coat somehow. I often used to run to the chemistry faculty
or to the main building without one.
I stopped short, with a start of fear. Well, that was all I needed. I had
almost fallen under the wheels of a huge lorry. The driver leaned out of the
cab and some highly original swearing burst into the pure, biting air, along
with the pearly steam from his breath. I broke out laughing. Aren't you the
fool, though, driver! I'm nothing but a vision. Come on, try again! Your
lawyer can get you off. You can't kill someone who doesn't exist.
What nonsense comes into one's head at times. I must try to keep my mind
about me, and not let it go woolgathering. I've got to remember I'm a sort of
stranger here.
A gaily-dressed line of students come towards me. Careless and proud,
they swing along like the Musketeers after a victorious bout with the
cardinal's guards. With a bit of a swagger, full of loud laughter and
impetuous boasting.
"What did you get, Penguin?" cried a tall fop of a fellow, turning to a
short red-head.
"A mere trifle! Only absorption, Langmuir's isotherm, the double electric
layer and the bi-structural model of water.... I could do it with one hand
tied...."
"They've just taken their physical chemistry exam," I thought to myself,
and walked slower.
"Just take a look at what I'm wearing," said the red-head, pulling the collar
of a blue-and-white striped shirt out from under his scarf. "No idea how it
holds together! I take all my exams in it. Brings me luck! My suit's old,
too— I took my school exams in it."
I felt a sort of muted, yearning jealousy.
Here were the red granite steps. The Canadian blue spruce-trees. The
stone statue of bald-headed Butlerov, now wearing a rakish snow cap.
From habit, I reached into my pocket for the pass. My heart skipped a beat
and fell to my boots: but with exaggerated heartiness I greeted the hall
porter, thrust my half-opened pass under her very nose and ran to the lift.
Poor thing, I thought. If she had only seen the date on it! — 'Given to bearer
on....'
The red signal arrow lit up. One moment and the lift doors would open. I
wondered whether it would be better not to go up to the third floor. What if I
met HIM and somebody saw us together? I went cold all over at the very thought.
As for going home, that was also out. My parents would never live
through it. They must not know anything about it. But to HIM, if I really did
meet him, I'd have to spill it all out at once.
I even laughed when I thought of HIM. Humour, probably, is in direct
proportion to how unusual and unnatural a situation is. And to think that
such a change had happened in an instant! In any case, subjectively, it was
an instant. But objectively? How much time had really passed since the
moment when I pulled the black cover off, at my thesis defence?

* * *

My theoretical premise aroused no particular opposition, not from
anybody. My chief, naturally, gave it a brilliant testimonial, while my
official opponents confined themselves only to the odd detail.
One of them, Professor Prosokhin, took a long time polishing his glasses
with a handkerchief, breathing on each lens, and then cleared his throat.
Slowly, his voice as squeaky as an un-greased wheel, he muttered something
as he bent over his papers. All these people were perfectly indifferent: no
matter how many chapters, pages and drawings in the dissertation, no matter
how big the bibliography, from foreign works or ours. The Scientific
Council had already estimated the work in their minds, and now listened
with bored expressions to the scrupulous but tiresome old professor. From
time to time, I put in tick marks, jotting down the odd phrase. My answering
address was still ahead of me. At last, Professor Prosokhin finished his
speech with the sacramental ending:
"However, the drawbacks I've mentioned do not in the least belittle the
importance of the work in question; it answers all the demands laid down for
a work of this kind, and its author, without a shadow of doubt, deserves to
be awarded the degree of Candidate of Physico-Mathema-tical Science."
Chairman of the Scientific Council Professor Valentinov, tall and
handsome, with aluminium-gray hair, gave a dignified cough and inquired:
"Will the candidate answer both opponents at once, or separately?"
"At once! Both together!" the cries broke out from the audience hall,
because the Scientific Council members were already fed up with the
sameness of the procedures of defence.
"Well, in that case," said Valentinov, with the charming smile of a peer
receiving the Order of the Garter, "we will call upon our honoured guest,
Samson Ivanovich Gogotseridze."
Corresponding Member Gogotseridze flew up on the rostrum like a Djigit
mounting his horse. He cast a fierce look round the auditorium and, having
intimidated nobody, burst into rapid-fire speech.
"The thorough and painstaking analysis made by our much honoured
Professor Sergei Alexan-drovich Prosokhin relieves me of the need of
making a detailed review of the thesis presented by the respected candidate,
Viktor Arkadye-vich." (A benevolent nod in my direction.) "So I shall dwell
only on several deficiencies in the work. There are but a few, and they are lost in the mass of positive material presented."
Gogotseridze paused for breath and mopped his red face with a snow-
white handkerchief.
"Ye-es. I shan't speak of the work's merits, but only briefly on its
deficiencies."
His 'briefly' stretched out for seventeen minutes. I had already begun
getting a bit nervous, but my chief gave me a barely noticeable wink, and I
cooled down. After enumerating all the deficiencies, Gogotseridze emptied a
glass of mineral water and pronounced the traditional conclusion that, apart
from this and that, the thesis answered the demands required and the
candidate deserved his scientific degree.
I rose from my seat to make my answering address. As nobody had
defeated me, and the particular details my opponents had not liked were far
from vital ones, I decided against a rude or tactless answer. For five minutes
I thanked all those who had helped me in my work. This was practically the
most important thing. But God help me, should I forget anybody! Then I
humbled myself before my opponents, promising to take all their remarks
into consideration during my subsequent work and, in general, to be guided
by their valuable advice.
My chief kept nodding in time with my every word. Everything was going
fine.
Then Valentinov called on the listeners to take part. But nobody was in a
hurry to speak. Unwillingly, as if in duty bound, one of the Council
members rose, mumbled a word or two, and resumed his seat. Somebody
else spoke for five minutes on abstract topics and sa